1. Field of the Invention
The present invention is generally related to cellular communication systems, and specifically to digital advanced mobile phone service (D-AMPS) cellular communication systems operating on an IS-54B or an IS-136 air interface standard.
2. Description of the Related Art
The evolution of wireless communication over the past century, since Guglielmo Marconi""s 1897 demonstration of radio""s ability to provide continuous contact with ships sailing the English Channel, has been remarkable. Since Marconi""s discovery, new wireline and wireless communication methods, services and standards have been adopted by people throughout the world. This evolution has been accelerating, particularly over the last ten years, during which the mobile radio communications industry has grown by orders of magnitude, fueled by numerous technological advances that have made portable radio equipment smaller, cheaper and more reliable. The exponential growth of mobile telephony will continue to rise in the coming decades as well, as this wireless network interacts with and eventually overtakes the existing wireline networks.
As traffic volume in cellular communication systems has been increasing dramatically, this increase in traffic volume causes subscribers to receive busy signals when trying to access the cellular communication system and to be dropped from the cellular communication system.
To alleviate congestion problems caused by high traffic volume residing on macro cells in a cellular communication system, micro and pico cells are introduced in the macro cells. As is understood to those skilled in the art, hot spots or small areas where high traffic volume congregates are usually time dependant, and are a main cause of call drops and unsuccessful setups. By adding micro and pico cells to the cellular communication system or network, the traffic congestion found in the hot spots may be offloaded from macro cells having high traffic volume to new micro or pico cells added to the system. When adding new micro and/or pico cells, a careful determination needs to be made as to the location to place the new micro and/or pico cells so that a maximum amount of traffic volume can be offloaded from the macro cell. At present, the method for finding the optimal locations to offload the maximum traffic volume from existing macro cells is rather subjective.
Typical cellular communication system operators rely on non-scientific information, such as visual inspections and customer complaints, of the suspected areas in order to determine the congestion locations. The cellular communication system operators further use the non-scientific information to determine locations for placing new micro or pico cells to resolve the traffic congestion. However, these non-scientific information sources are highly speculative and do not provide any quantitative analysis to determine an optimum or best location for placing the new micro or pico cells.
The present invention is a system and method to provide a scientific and quantitative measurement in finding optimal locations for placing new micro or pico cells. Signal strength information of a test transmitter measured by mobile stations is reported to a base station serving a macro cell that the mobile stations are located. The signal strength information is reported via call quality messages (CQM). Once the base station receives the call quality messages, a post-processing tool counts the number of call quality messages during a measuring period having a signal strength level measured from the test transmitter above a threshold indicating that a call can be offloaded to the new micro or pico cell. An estimated offloaded traffic volume is then calculated, preferably in Erlangs.